This invention relates generally to power operated doors for passenger control in mass transit vehicles, of the type where the door panel essentially plugs and unplugs an opening in the car side wall in door opening and door closing operations.
Typically, systems of this type are disclosed and claimed in the above-mentioned co-pending application and other door systems disclosed and claimed in issued patents, including U.S. Pat. No. 5,263,280. While these systems operate successfully and many are in use today, a difficulty arises in that for the unplugged door opened position the door panel is located out of the opening and adjacent the vehicular side wall. Also, in order to insure that the passenger opening is not obstructed by the panel in its opened position, it is common practice to support the door panel by an attachment to the operator at or near its inside or passenger interfacing edge and along the panel upper edges. Under these conditions, the door panel is essentially cantilevered outward of the upper inside support, resulting in substantial strain on the operator and/or hanger utilized. This strain results in a certain amount of door sag or downward deflection from a horizontal position. An additional difficulty of the above-described support comes from the large leverage on the operator support for forces applied to the door panel lower edge.
Further, the elasticity of the cantilevered door support system allows a substantial amount of door oscillation when moving from closed to open, the door panel stops in the opened position alongside the car body. This oscillation motion is compound in that it has amplitude components, both perpendicular and parallel to the door panel.
Generally speaking, the resilient nature of the operator drive and large door panel to operator leverage characteristics of these systems is undesirable in that damage to or high wear rate on the operator can occur either from repeated normal operation, passenger contact with the door panel, or deliberate acts of vandalism, i.e., forcing the panel away from the car body by individuals outside the car.
The invention disclosed herein overcomes the difficulties discussed above in that it provides a substantial and positive mechanical support to the door panel. Incorporation of the door panel support action into the door opening sequence locks the panel in place immediately on reaching an open position, thereby minimizing panel oscillation and possibilities for other damage.
Accordingly, therefore, it is an object of this invention to provide a means for stabilizing door panel of a sliding plug door system when in opened position.
It is a further object of this invention to prevent damage to the operator drive of an outside sliding plug door system by resisting external and undesirable forces applied to the panel when in an opened position.
It is an additional object of this invention to minimize passenger hazards due to the panel oscillation when an outside sliding plug door is moved from closed to open.
It is a further object of this invention to provide a sequenced door support for panels of an outside sliding plug door system, wherein a movable door support corrects the panel's outboard sag in an opened position.